Hello everyone, hoping someone might be able to help me out a bit here. My 97 A4 2.8L 12 Valve, is currently giving me code P1106, saying it’s an air leak, read on my OBDeleven. For the past 6 months the car has been parked in my garage after it was “diagnosed” with a head gasket failure by a local mechanic via compression test on the coolant system. (Had a really nasty coolant leak on the front of the block, told them I think it’s the water pump but they insisted it’s the head gasket, even though I never had coolant / oil mixing, just a loss of both of them, more so the coolant than oil.)




I finally decided to start working on it these past few weeks. Ordered and replaced the thermostat, water pump, idler roller, tensioner roller, timing belt, fan belt, valve cover gaskets, air filter, oil and oil filter, & battery. Also ordered the cam locking bar and crank lock tool to be sure not to screw anything up during all that as this was my very first timing belt job on any car before. So far so good. Got the car up and running, did have a really bad knocking sound on the first start, but letting it idle for about 10 minutes got rid of the sound.




I also decided to take out the entire AC system including the lines and compressor as the AC has never worked since owning the car, and I knew the compressor was shot when I went to get the Freon drained. I did however replace the AC Evap core about a year ago when I did the heater core so at some point I’ll get to fixing the AC but not till everything else is fixed. I ended up getting shorter fan belt to bypass the now removed compressor.




Anyways, the car has been running really good since I got everything done the other day, drove it about 50 miles or so. Then while letting it idle for about 20-30 minutes or so checking for any leaks (been extremely paranoid I’m gonna find another one) the CEL clicked on. I connected my OBDeleven reader and got P1106. Did a bit of research and saw that it’s recommended to replace the O2 sensors. Well about a year ago when I did the heater core and evap I also did both of the upstream O2 sensors, so it’s definitely not those.




Now what I’m thinking is the problem is the vacuum lines. Reason being is that about a year and a half ago I had to replace my intake manifold gasket. Which involved removing the EGR and majority of the vacuum lines which were in horrible condition (cracking, broken, missing). So I replaced all the vacuum lines and did my best to follow the diagram under the hood to connect them back together right. However I could never seem to get them right and I do remember still getting codes related to air leaks in the past before being parked in my garage for 6 months. I’ve tried going to junk yards, but can’t seem to find a 12 valve variant with the vacuum lines still intact, googling online can’t find anything either. Poking around the engine bay I found a random vacuum line coming out of the back of the engine block, right next to the EGR (not going in the EGR, but next to it) that’s not connected to anything. I can’t seem to find where it needs to go to. So I capped it with a spare screw, cleared the code, and am currently waiting to see if it’ll come back on, which is highly likely.




Does anyone happen to have a 2.8L 12 valve that they wouldn’t mind sharing their vacuum hose setup with me? Does this code even relate with the vacuum lines at all or am I looking at a bigger issue here? Additionally the cruise control has never worked either, could that also be due to vacuum lines?

I think I may have fixed the CEL, during the T-Belt job I threw away the engine air filter and didn’t get a new one untill about 30 miles were put on the car after the job. After putting the new filter in and clearing the code I’ve driven it about 120 miles and no CEL or codes anymore. Could also be that vacuum line I plugged with a screw. Guess only time will tell to see if it turns on again.

I do still have an oil leak from the rear passenger side of the engine. I’m suspecting it’s coming from the rear cam seal. But im not to sure.
It’s dripping off of what I’m guessing is the skid plate bracet (circled in red) on the passenger side.


I see a lot of oil residue build on this particular wire below the cam. I’ll try to get a better picture down there.